Shirt dilemma

Going to Xmas dinner with work tomorrow night and dress code is smart. Was planning on wearing brown suit trousers, cream shirt with hidden buttons, no tie. Is this acceptable? Should I also wear my suit jacket?

Think the dress code is "don't dress like a bum"....it's a fancy hotel we're going to.
What's wrong with what I'm planning on wearing Rooster?
Haven't got a decent sport coat hence why I was just gonna pull on the matching suit jacket.

Put the jacket on. "Smart" should be a notch up from what most people wear on the street. Trousers and shirt with neither tie nor jacket isn't much different than what most people wear daily.

There used to be a time when moderately upscale restaurants would not even seat you without a jacket. Some even had extra jackets in the coatroom so that if you showed up without one, you could borrow one for the evening.

Put the jacket on. "Smart" should be a notch up from what most people wear on the street. Trousers and shirt with neither tie nor jacket isn't much different than what most people wear daily.
There used to be a time when moderately upscale restaurants would not even seat you without a jacket. Some even had extra jackets in the coatroom so that if you showed up without one, you could borrow one for the evening.

Agreed. And I was amazed, Del Posto in NYC used to require a jacket, or at least strongly recommended it. Last time I was there they seated a guy with torn jeans and an untucked casual shirt... It's really frustrating how everything is becoming so casual.